Ocean! This word sounds loud and menacing. This is one of a kind huge accumulation of water surrounding continents and islands. This is the boundless sea that washes the universe. But, I wonder what kind of water is in the ocean, what is its chemical composition?
Chemical composition of ocean water
Ordinary residents often deal with fresh water, which contains almost no foreign impurities. However, it also contains dissolved salts, although in small concentrations. What then can we say about the ocean? What is the water like in the ocean? Judging by its composition, the ocean can hardly be called water. It is very similar to strong salty brine. Each kilogram of it contains about 35 grams of various salts. Scientists have found that chemical compounds of all elements are dissolved in the ocean.
Salt in the ocean
The fact that there is salt water in the ocean is an undeniable fact. But in different parts of the World Ocean, the concentration of salt is different. The Atlantic is considered the saltiest of all oceans, although some scientists consider the Indian Ocean to be the saltiest. And the least salty is the water of the Gulf of Finland. Despite the fact that salinity differs in different parts of the World Ocean, the ratio of different salts in water is the same. This amazing constancy is explained by the mixing of water by waves and currents.
Is there an ocean with fresh water
Fresh water in the ocean? This is impossible! Although there are hypotheses in science, they are just assumptions. This desalination is explained by the influence of powerful rivers flowing into the ocean and heavy precipitation in temperate latitudes. However, the rivers that flow towards the ocean do not contain pure fresh water. Rivers wash away rocks and, washing away salts, carry them into the ocean. And let's not forget about the water cycle. After evaporation, ocean water falls as rain or snow, collects in rivers and returns to the ocean. Thus, salinization of the ocean continues today.
Why is the water in the ocean salty and the water in rivers fresh? The answer to this question is ambiguous. There are different points of view that reveal the essence of the problem. According to scientists, it all comes down to the ability of water to destroy rock and leach easily soluble components from it, which end up in the ocean. This process occurs continuously. Salts saturate sea water, giving it a bitter-salty taste.
Everything seems to be clear, but at the same time, there are two diametrically opposed opinions on this issue. The first comes down to the fact that all the salts dissolved in the water are carried by rivers into the ocean, saturating the sea water. There are 70 times less salts in river water, so it is impossible to determine their presence in it without special tests. It seems to us that the river water is fresh. In fact, this is not entirely true. Seawater is constantly saturated with salts. This is also facilitated by the process of evaporation, as a result of which the amount of salts constantly increases. This process is endless and lasts about two billion years. This is enough time to make the water salty.
The composition of sea water is quite complex. It contains almost the entire periodic table. But most of all, it contains sodium chloride, which makes it salty. By the way, in closed lakes the water is also salty, which confirms the correctness of this hypothesis.
Everything seems to be correct, but there is one thing! Sea water contains salts of hydrochloric acid, and river water contains carbonic acid. That is why scientists have put forward an alternative hypothesis. They believe that sea water was originally salty, and rivers have absolutely nothing to do with it. This is all due to volcanic activity, the peak of which occurred at the time of the formation of the earth’s crust. Volcanoes released huge amounts of steam saturated with acids into the atmosphere, which condensed and fell to the ground in the form of acid rain. The sediments saturated the seawater with acid, which reacted with the hard basaltic rocks. As a result, huge amounts of alkali were released, including sodium, potassium and calcium. The resulting salt neutralized the acid in seawater.
Over time, volcanic activity decreased, the atmosphere was cleared of vapors, and less and less acid rain fell. About 500 million years ago, the composition of sea water stabilized and became what we know it today. But the carbonates that enter the ocean with river water serve as an ideal building material for marine organisms. They build coral islands, shells, and their skeletons from it.
Which hypothesis to choose is a purely personal matter. In our opinion, they both have a right to exist.
Have you ever wondered what you would do if you were stranded on a desert island in the open ocean? You would first want to find food, make fire, make shelter and find water. Water? That's right, and although you may be surrounded by an endless ocean, those of you who have been to a sea beach know that sea water is not suitable for drinking.
Why not? Because . But why is sea water salty and not suitable for drinking?
Ocean water is salty because it contains large amounts of dissolved minerals. These minerals are often called "salts". Depending on where you are in the world, seawater contains approximately 3.5% salts. The water around it has a high salinity, while the northern waters contain less salts.
At the bottom there is a huge amount of minerals that are destroyed and rise to the surface by natural ocean currents. As the movement of water and waves erodes the ocean floor, minerals dissolve in the water and the amount of salts increases. This is how the ocean constantly replenishes its salinity.
Oceans and seas also get some of their salt from streams, rivers and lakes. While this may seem counterintuitive since these bodies of water contain fresh water, you may be surprised to learn that all lakes, rivers and streams contain some amount of dissolved salts. However, the concentration of salts in these bodies of water is much less than in the oceans, so their water appears less salty than ocean water.
Salts cannot accumulate in most lakes because they have outlets such as rivers and streams. These outlets allow water to flow to the oceans, carrying minerals with the flow.
On the other hand, it is an example of a reservoir without an outlet. Minerals that flow into the Dead Sea cannot be released into the open ocean because there is no runoff. Because of this, the Dead Sea contains some of the saltiest water on Earth.
In fact, up to 35% of the salts are found in the waters of the Dead Sea! This is almost ten times more than the concentration of salt in the oceans. The salty water of the Dead Sea is lethal to most living things, which is why you won't find any fish or sea creatures there. Only a few species of bacteria and algae can survive the harsh conditions of the Dead Sea. That's why it's called Dead!
While you certainly wouldn't want to drink the water from this sea, you can swim in it. Due to the high concentration of salt, the density of water in the Dead Sea is much greater than in fresh water. This allows the swimmer to stay well on the surface of the water. Diving into the Dead Sea is a bit like dropping a plastic lid into a bowl of water. The dense water makes it easy to swim, even without much effort. In fact, water makes swimmers so buoyant that it is very difficult for them to reach the bottom or swim underwater.
Often, sailors of ships that were wrecked or lost in sea waters died of thirst. But few people know why this is so, because there is a lot of water around.
The thing is that sea water is saturated with such a composition that it is not suitable for the human body and does not quench thirst. In addition, sea water has a specific taste, bitter and salty, and is not suitable for drinking. This is all due to the salts dissolved in it. Let's figure out how they got there.
What gives water its salty taste?
Salt has a crystalline appearance. Ocean waters contain almost all elements of the periodic table. Hydrogen and oxygen combine to form water molecules. It also contains impurities of fluorine, iodine, calcium, sulfur and bromine. The mineral base of sea water is dominated by chlorine and sodium (ordinary salt). This is why the water in the sea is salty. It remains to be seen how the salts get into this water.
Related materials:
The deepest seas in the world
How sea water was formed
Scientists have been conducting experiments for a long time and trying to figure out why sea water is salty and river water is fresh. There are several theories about the formation of salty sea water.
It turns out that rivers and lakes also have salty water. But the salt content in them is so small that it is almost unnoticeable. According to the first theory, river waters entering the seas and oceans evaporate, but salts and minerals remain. Because of this, their concentration increases all the time and the water in the sea and ocean becomes salty.
According to scientists, the process of salinization of the seas has been going on for a billion years. But contrary to the first theory, it has been proven that the waters in the world's oceans have not changed their chemical composition for a long time. And those elements that come with river water only maintain the oceanic composition, but do not change it in any way. This leads to another theory. Salt has a crystalline consistency. Waves hitting the shore wash the stones. Lures form in them. When the water evaporates, salt crystals remain in these holes. When the rock breaks down, the salt gets back into the water and it becomes salty.
Related materials:
The warmest seas in the world
Consequence of volcanic activity
Scientists have concluded that the water in the seas was salty back in the days when humanity did not exist on the planet. And the reason for this was volcanoes. The earth's crust was formed over many years by the emission of magma. And volcanic gases contain chemical combinations of chlorine, fluorine and bromine. They entered the ocean waters in the form of acid rain, and initially the water in the ocean was acidic. This water broke up the crystalline rocks of the earth's crust, and extracted magnesium, potassium and calcium. These acids began to form salts as a result of reaction with hard earth rocks. Few people know that the salt we are used to is formed as a result of the reaction of perchloric acid from the ocean and sodium ions from volcanic rocks.
Anyone who was on the beach could see that the water in the sea tasted salty. But where does salt come from if fresh water enters the ocean through rains, rivers, etc.? Why is the sea salty and has it always been like this - time to figure it out!
How is water salinity determined?
Salinity refers to the salt content in water. Most often, salinity is measured in " ppm » (‰). Permille is one thousandth of a number. Let's give an example: a water salinity of 27 ‰ will mean that one liter of water (this is approximately 1000 grams) contains 27 grams of salt.
Water with an average salinity of 0.146 ‰ is considered fresh.
Average The salinity of the World Ocean is 35 ‰. What makes water salty is sodium chloride, also known as table salt. Among other salts, its share in sea water is the highest.
The saltiest sea is the Red Sea. Its salinity is 41‰.
Where does salt come from in the seas and oceans?
Scientists still disagree about whether seawater was originally salty or acquired such properties over time. Depending on the versions, different sources of the appearance of salts in the World Ocean are considered.
Rains and rivers
Fresh water always has a small amount of salts, and rainwater is no exception. It always contains traces of dissolved substances that were captured during its passage through the atmosphere. Getting into the soil, rainwater washes away a small amount of salts and eventually carries them to lakes and seas. From the surface of the latter, water intensively evaporates, falls again in the form of rain and brings new minerals from the land. The sea is salty because all the salts remain in it.
The same principle applies to rivers. Each of them is not completely fresh, but contains small amounts of salts captured on land.
Confirmation of the theory - salt lakes
Proof that salt comes through rivers are the saltiest lakes: the Great Salt Lake and the Dead Sea. Both are about 10 times saltier than seawater. Why are these lakes salty?, while most of the world's lakes are not?
Lakes are usually temporary storage areas for water. Rivers and streams bring water to lakes, and other rivers carry it away from these lakes. That is, water comes in from one end and leaves from the other.
The Great Salt Lake, the Dead Sea and other salt lakes have no outlets. All the water that flows into these lakes leaves only through evaporation. When water evaporates, dissolved salts remain in bodies of water. Thus, some lakes are salty because:
- the rivers carried salt to them;
- the water in the lakes evaporated;
- the salt remained.
Over many years, salt in the lake water has accumulated to its current level.
Interesting fact: The density of salt water in the Dead Sea is so high that it practically pushes a person out, preventing him from sinking.
The same process made the seas salty. Rivers carry dissolved salts to the ocean. Water evaporates from the oceans to fall again as rain and replenish rivers, but the salts remain in the ocean.
Hydrothermal processes
Rivers and rain are not the only source of dissolved salts. Not long ago, they were discovered on the ocean floor hydrothermal vents. They represent places where seawater has seeped into the rocks of the Earth's crust, become hotter, and is now flowing back into the ocean. Along with it comes a large amount of dissolved minerals.
Submarine volcanism
Another source of salts in the oceans is underwater volcanism - volcanic eruption underwater. It is similar to the previous process in that seawater reacts with hot volcanic products and dissolves some of the mineral components.
